Various types of push switches are used for input sections of electronic devices. A push switch which is activated by pushing an operation body of the switch in parallel to a surface of a board the push switch is mounted onto is often used.
FIG. 9 is a plan view of a conventional push switch 501 disclosed in Japanese Patent Laid-Open Publication No. 2005-122989. FIG. 10 is a cross sectional view of push switch 501 at line 10-10 shown in FIG. 9.
Case 1 made of resin material has a recess opening upward. Inner fixed contact 2A and an outer fixed contact are located in the recess and are fixed unitarily within case 1. Terminals 5 connected with inner fixed contact 2A and the outer fixed contact protrude from side surfaces of case 1 opposite to each other, respectively. Terminals 5 have ends which are bent up, and have shapes suitable for being mounted onto the surface of a board.
Movable contact 7 is made of a thin metal plate. Movable contact 7 is accommodated in the recess of case 1, and has its outer circumference placed on the outer fixed contact. The recess of case 1 is covered with protection film 8 adhered onto on an upper surface of case 1. Movable contact 7 has a square shape, or circular shape.
Operation body 10 made of resin material includes operation portion 10A protruding to the front and driving portion 10B located behind operation portion 10A. Operation body 10 is placed on protection film 8 such that the operation body is movable in front and back directions on the upper surface of case 1.
Metal cover 15 covers case 1 with operation body 10 between the cover and the case. Slope portion 15A is formed at the central part of metal cover 15 and inclines towards case 1. Slope portion 15A is positioned behind driving portion 10B. An end of driving portion 10B contacts a front surface of slope portion 15A which inclines. Metal cover 15 has leg 15B which can be soldered and which protrudes downward at the side surface of case 1.
FIG. 11 is a side view of push switch 501 mounted on surface 501C of board 501A. Operation portion 10A protrudes to the front from end 501B of board 501A. Terminals 5 are connected with surfaces of corresponding lands by soldering, thereby mounting push switch 501 on surface 501C of board 501A. Leg 15B of metal cover 15 is also soldered to a land corresponding to the leg. Terminals 5 are drawn from both side surfaces of case 1 such that terminals 5 protrude perpendicularly to front and back directions, i.e., a moving direction of operation portion 10A. Terminals 5 are fixed to the board with solder such that respective ends of terminals 5 which are bent up are in parallel with the moving direction of operation portion 10A.
If an operating force is applied to operation portion 10A for pushing operation portion 10A in a direction parallel to surface 501C, operation body 10 moves along the parallel direction by sliding on protection film 8 covering the upper surface of case 1. Then, the end of driving portion 10B is guided downward along slope portion 15A to apply a downward force to movable contact 7 located beneath slope portion 15A.
When the downward force exceeds a predetermined level, movable contact 7 is inverted at the central part and has its central bottom contact inner fixed contact 2A. Thereby, terminals 5 are connected via movable contact 7, thus turning on push switch 501.
Upon the force applied to operation portion 10A being released, movable contact 7 returns to have its original shape by its restoring force and pushes driving portion 10B upward. Driving portion 10B which is pushed up is guided along slope portion 15A and causes operation body 10 to be pushed back to the front, thereby turning off push switch 501, as shown in FIG. 10.
In the conventional push switch 501, soldered portions of terminals 5 and leg 15B of metal cover 15 receive the operating force applied to operation portion 10A. Even if push switch 501 is small in size, a certain clearance between leg 15B and terminals 5 are necessary to avoid possible mutual contact of solder applied to terminals 5 and leg 15B. This structure accordingly prevents push switch 501 from having a small size.
If the number of constituent members, such as terminal 5 and leg 15B, which are connected with board 501A, is decreased in order to reduce the size of push switch 501 and to allow the push switch to be suitable for a portable device, board 501A may be removed when the portable device is dropped.